The term "Web 2.0" refers to a perceived second generation of web development and design, that aims to facilitate communication, secure information sharing, interoperability, and collaboration on the World Wide Web. Web 2.0 concepts have led to the development and evolution of web-based communities, hosted services, and applications; such as social-networking sites, video-sharing sites, wikis, blogs, and folksonomies.

The term was first used by Dale Dougherty and Craig Cline and shortly after became notable after the O'Reilly Media Web 2.0 conference in 2004.[1][2] Although the term suggests a new version of the World Wide Web, it does not refer to an update to any technical specifications, but rather to changes in the ways software developers and end-users utilize the Web. According to Tim O'Reilly:

“Web 2.0 is the business revolution in the computer industry caused by the move to the Internet as a platform, and an attempt to understand the rules for success on that new platform.[3] ” O'Reilly has said that the "2.0" refers to the historical context of web businesses "coming back" after the 2001 collapse of the dot-com bubble, in addition to the distinguishing characteristics of the projects that survived the bust or thrived thereafter.[4]

Tim Berners-Lee, inventor of the World Wide Web, has questioned whether one can use the term in any meaningful way, since many of the technological components of Web 2.0 have existed since the early days of the Web.